diff --git a/packages/experiment-browser/src/types/user.ts b/packages/experiment-browser/src/types/user.ts
index 7cb08a46..ac77855a 100644
--- a/packages/experiment-browser/src/types/user.ts
+++ b/packages/experiment-browser/src/types/user.ts
@@ -76,6 +76,11 @@ export type ExperimentUser = {
    */
   library?: string;
 
+  /**
+   * Predefined field, can be manually provided
+   */
+  ip_address?: string;
+
   /**
    * The time first saw this user, stored in local storage, can be manually overridden
    */